Carbon monoxide is known to react with components in meat and fish to maintain a consumer-preferred fresh-cut coloration of the meat or fish. For this reason carbon monoxide is often introduced into packaged meat and fish at concentrations of about 0.2% to 5% to enhance the products consumer appeal. Unfortunately, the coloration created by the use of excessive carbon monoxide can mask the normal visual indications of spoilage. Hence, the meat packaging industry, as well as those in the distribution chain, are seeking ways to monitor and control the concentration of carbon monoxide introduced into packaged meat and fish to attain a proper balancing of consumer preference for fresh colored meat and fish with the need for a visual indication of spoilage.
A wide range of sensors are known and available for detecting carbon monoxide levels, including electrochemical sensors, infrared sensors and tin oxide sensors. While each type of sensor possesses various combinations of benefits and detriments (e.g., level of resolution, cost, sensitivity to other variables such as temperature and humidity, etc.) such sensors are generally overly sensitive to other components in a gas sample or are subject to overrange at concentrations in excess of about 1,000 to 1,500 ppm (i.e., 0.1% to 0.15%). Hence, while such sensors are effective for detecting toxic levels of carbon monoxide in air, they are not suitable for use in measuring the concentration of carbon monoxide in environments having potentially high concentration of carbon monoxide, such as packaged meat and fish.
Accordingly, a substantial need exists for an inexpensive, high resolution sensor capable of accurately measuring carbon monoxide levels over an extended range.